When an NSAID is applied to the skin over the site of pain, the medicine is delivered more directly. While the drug does not enter the gastrointestinal tract, some of the drug does get absorbed into the blood stream, so topical NSAIDs are not completely free of potential side effects.

Topical NSAIDs are likely to be most effective for joints nearer the surface of the skin, where the medication can more easily penetrate the affected area. They may be less effective for joints deeper in the body, such as the spine.